瘟疫非伤寒也，世医误以为伤寒矣。伤寒感天地之常气，此感天地之厉气也。
邪自口鼻入，内不客脏腑，外不客经，舍于伏脊之内，去表不远，附近于胃，
乃表里分界，是为半表半里，《针经》）所谓横连膜原是也。凡邪在经为表，在胃
为里，今邪在膜原，正当经胃交关之所。病之始发，凛凛恶寒，甚则厥逆，阳热郁
极而通，则厥回而中外皆热。始而恶寒，既而发热，非若伤寒发热而兼恶寒也。瘟
初起，先憎寒后发热，头痛身疼，脉洪而数，其脉不浮不沉，盖以邪在膜原故也。
不可认为伤寒表证而发其汗，邪不在经，汗之徒伤。又不可下，邪不在里，下之无
益。宜达原饮疏之，槟榔二钱，浓朴一钱，草果五分，知母一钱，芍药、黄芩各一
钱，甘草五分，午后温服。上槟榔、浓朴、草果三味，消滞破结，协力并逐，
使邪气速离膜原。后四味为滋液和血、清燥和中之用。（按此汤初起可用，若病成热炽，用此
恐无济。有表者宜用河间双解散，无表者宜用东垣二圣救苦丹。以及凉膈、白虎
、黄连解毒、普济消毒等剂。俱对
证之药，酌用可也。）其邪气游溢诸经不同，本方加减法∶胁痛耳聋，寒热。呕而口苦，
邪溢于少阳也，加柴胡（一钱）；腰背项痛，邪溢于太阳也，加羌活（一钱）；目痛，眉棱骨
痛，眼眶痛，鼻干，不眠，邪溢于阳明也，加干葛（一钱）。若不见三阳经证，不必加药，
止照本方。（以上论初起用达原饮。）
服此药其邪不传里者，一二剂自解。其证候∶头痛身痛，发热而复凛凛，但内
无胸满腹胀等证，谷食不绝，不烦不渴，此邪气外传，由肌表出。或自发斑消，或
从出汗解。斑有斑疹、桃花斑、紫云斑。汗有自汗、盗汗、狂汗之异。此病气使然，
不必较论，但求得斑、得汗为愈病耳。此邪自外传，顺证也，勿药亦能自愈。
其有汗出不彻而热不退者，宜白虎汤∶生石膏、（一两。）知母、甘草、（各五钱。）粳米
（一撮）服此药辛凉解散，或战汗或自汗而解。盖前服达原饮，毒结渐开，邪气已离膜
原，尚未出表，然内外之气已通，故多汗、脉长洪数，故宜白虎辛凉散之也。其有
斑出不透而热不退者，宜举斑汤∶白芍、当归、（各一钱。）升麻（五分）、白芷、柴胡、（各七分。）
穿山甲，（二钱炙黄。）水姜煎服。其有斑汗并行而热不除者，宜白虎（合）举斑汤。斑汗既
愈，一二日或四五日后，根据前发热，无胸满腹胀等证，脉洪而数，此膜原有隐伏之
邪，发未尽也。勿药，一二日间当仍自汗自斑而愈。未愈者，仍根据前法治之，然亦
少有，至于再三发者，更少有也。（以上论邪传表。）
若服达原饮而无汗无斑，外亦无头疼身痛，惟胸膈痞满，此邪传里也。有欲吐
不吐者，有得少吐不快者，邪传里之上也，宜瓜蒂散吐之。甜瓜蒂（一钱）赤小豆（二钱）
研、生栀仁（二钱），用水二钟，煎至一钟，后入赤豆煎至八分，先服四分，一时后不吐，
再服，尽吐之。如未尽，烦满尚存者，再煎服。如无瓜蒂，以淡豆豉二钱代之。此
病饮食不能，胸膈烦而腹不满，吐之则邪减，邪尽病自已。有心腹胀满，不呕不吐，
或燥结便闭，或热结旁流，或协热下利，或大肠胶闭，邪传里之中、下也，宜承气
汤∶大黄（五钱） 浓朴（一钱） 枳实（一钱） 芒硝（二钱） 若但上焦痞满，无便结等病，去芒硝，
即小承气汤也。然虽无结粪，而大便粘腻极臭者，亦加之。若不痞满，止便结者，
去浓朴、枳实，芒硝用二钱五分，加甘草一钱，即调胃承气汤也。服此导去其邪，
邪减病自减，邪尽病自已。有胸膈满闷，心腹胀满，下部热结胶粘者，此上中皆病
也。不可吐，吐之为逆，但用承气汤，则上邪顺流而下，呕吐立止，胀满渐除。其
有吐后、下后既愈，二三日或四五日根据前复发者，在上者仍用吐药，在下仍用下药。
此为再里之证，常事也。甚有三发者，亦少有。（以上论邪传里。）
若服达原饮后，或病失治，而三阳证悉具，里证亦具，又舌根先白胎，至此时
根黄至中央，此表里分传也。其证∶外则身热头痛，身疼，腰背项痛，眉棱痛，口
苦耳聋，鼻干；内则胸膈心腹满闷，下部热结。此瘟病常事也，断不可强求其汗，
宜用承气汤先通其里，里邪去则气通，乘势尽发于肌表矣。若表里证悉去而热仍不
退，（此膜原之邪未尽也。）宜三消饮∶槟榔、草果、浓朴、白芍、甘草、知母、黄芩、大
黄、干葛、羌活、柴胡、姜、枣煎服，调之可愈。服药既愈，三两日复发者，仍用
三消饮复下复汗，如前而愈，此亦常事也。至有三发者，亦少有。若表邪多里证少，
当治表兼治里，三消饮，大黄少用。若里证多表证少，但治里，或吐或下，表证自
愈。（以上论表里分传。）
若始病但发热、头痛、身疼、口苦、鼻干，而内无里证，止宜达原饮加减法。
若不见三经病，止于发热，不用加法。继而脉洪大数，自汗而渴，邪离膜原，未能
出表也，宜白虎汤辛凉解散，脉静身凉而愈。愈后数日根据前发热，仍宜达原饮。至
后反加胸满腹胀，不思食，烦渴，舌上刺等证，皆由表传里也，达原饮加大黄微利
之。久而不去，在上者用吐方，在下者用承气下方。若始则发热，渐盖理病，既用
承气等汤下之，而里病除矣。数日内复发热，反加头痛身疼，此由里出表也，脉浮
者宜白虎汤。下后热减不甚，热虽无，头痛身疼，而三四日后精神不慧，脉浮者，
亦宜白虎汤汗之。若服白虎汤不得汗者，因精液枯竭也，加人参，覆卧则汗解。若
大下后、大汗后，表里证悉去矣，继而一身尽痛，身如被杖，甚则不可转侧，周
身骨寒而痛，（气血虚故痛耳。）非表证也，当自愈。（以上论表里递传。）
瘟疫并非伤寒，世间的医生误将其当作伤寒治疗了。伤寒感受的是天地间的常气（正常气候之气），而瘟疫感受的是天地间的厉气（疫疠毒邪）。
病邪从口鼻侵入，内部不侵犯脏腑，外部不侵犯经络，而是停留在伏脊之内的膜原部位。这里距离体表不远，靠近胃部，正是表与里的分界线，也就是《针经》所说的“横连膜原”。凡是病邪在经络属于表证，在胃腑属于里证，现在病邪在膜原，正好处于经络与胃腑交接的关键位置。
疾病刚开始发作时，患者感到阵阵恶寒，严重时出现四肢厥冷；当阳气郁积到极点而通达时，厥逆消退，全身内外都发热。起初是恶寒，随后发热，这与伤寒发热同时伴有恶寒不同。瘟疫初起，先憎寒后发热，头痛身疼，脉象洪大而数，脉位不浮不沉，这是因为病邪在膜原的缘故。
不能认为是伤寒表证而使用发汗法，因为邪气不在经络，发汗只会徒然损伤正气。也不可使用攻下法，因为邪气不在里部，攻下毫无益处。适宜使用达原饮来疏利透达，方药组成：槟榔二钱，厚朴一钱，草果五分，知母一钱，芍药、黄芩各一钱，甘草五分，午后温服。其中槟榔、厚朴、草果这三味药，能消滞破结，协力驱逐，使邪气迅速离开膜原。后四味药则是为了滋养津液、调和血液、清除燥热、调和中焦的作用。（按语：此方适用于初起阶段，若病情发展导致热势炽盛，使用此方恐怕无济于事。若有表证者宜用刘河间的双解散，无表证者宜用李东垣的二圣救苦丹。以及凉膈散、白虎汤、黄连解毒汤、普济消毒饮等剂型。这些都是对症的药物，酌情选用即可。）
如果邪气游溢于各条经络表现不同，本方加减法如下：胁痛耳聋，寒热往来，呕吐且口苦，这是邪气溢于少阳经，加柴胡一钱；腰背项部疼痛，这是邪气溢于太阳经，加羌活一钱；目痛，眉棱骨痛，眼眶痛，鼻干，失眠，这是邪气溢于阳明经，加干葛一钱。如果没有出现三阳经的症状，不必加药，只照原方服用。（以上论述初起使用达原饮。）
服用此药后，邪气若不传入里部，一二剂后即可自行解除。其证候表现为：头痛身痛，发热后又感到阵阵恶寒，但体内没有胸满腹胀等症状，饮食如常，不烦躁不口渴，这是邪气向外传变，由肌表排出。或者自发斑疹消退，或者通过出汗而解。斑疹有斑疹、桃花斑、紫云斑的区别；汗有自汗、盗汗、狂汗的不同。这是病气所致，不必过多争论，只要求得发斑或出汗，就是病愈的标志。这种邪气从外传出的情况，属于顺证，即使不用药也能自愈。
如果有汗出得不透彻而热不退的，适宜用白虎汤：生石膏一两，知母、甘草各五钱，粳米一撮。服用此药辛凉解散，或通过战汗或通过自汗而解。因为之前服用了达原饮，毒结逐渐解开，邪气已离开膜原，但尚未完全出表，然而内外之气已经通畅，所以多见多汗、脉长洪数，因此适宜用白虎汤辛凉发散。
如果有斑疹出不透而热不退的，适宜用举斑汤：白芍、当归各一钱，升麻五分，白芷、柴胡各七分，穿山甲二钱（炙黄），用水和生姜煎服。
斑疹和汗出既然后痊愈，过一二天或四五天后，又根据前状发热，没有胸满腹胀等症状，脉象洪大数，这是膜原有隐伏的邪气，未能彻底发散干净。不用药，一二日间应当仍然通过自汗或发斑而痊愈。未痊愈的，仍按照前面的方法治疗，但这情况很少，至于反复发热的，更是少有。（以上论述邪气传向体表。）
如果服用达原饮后无汗无斑，体外也没有头疼身痛，只有胸膈痞闷胀满，这是邪气传入里部。有的想吐却吐不出来，有的吐出少量后仍觉不快，这是邪气传入里部的上部，适宜用瓜蒂散催吐。甜瓜蒂一钱，赤小豆二钱研末，生栀子仁二钱，用水两钟，煎至一钟，后加入赤小豆煎至八分，先服用四分，一小时后若不吐，再服用，直到全部吐出为止。如果未吐尽，烦闷尚存的，再煎服。如果没有瓜蒂，可以用淡豆豉二钱代替。此病饮食难进，胸膈烦闷而腹部不满，催吐则邪气减少，邪气尽除病自然痊愈。有心腹胀满，不呕不吐，或者大便燥结闭阻，或者热结旁流，或者协热下利，或者大肠胶闭不通，这是邪气传入里部的中部、下部，适宜用承气汤：大黄五钱，厚朴一钱，枳实一钱，芒硝二钱。如果只是上焦痞满，没有大便结滞等疾病，去掉芒硝，就是小承气汤。然而虽然没有结粪，但大便粘腻极臭的，也要加上芒硝。如果不痞满，仅大便结滞的，去掉厚朴、枳实，芒硝用二钱五分，加甘草一钱，就是调胃承气汤。服用此方导引去除邪气，邪气减少病自然减轻，邪气尽除病自然痊愈。
有胸膈满闷，心腹胀满，下部热结胶粘的，这是上部和中部都有病。不可催吐，催吐为逆治，只用承气汤，则上部邪气顺流而下，呕吐立即停止，胀满逐渐消除。
有经过催吐、攻下后既已痊愈，二三天或四五天后又根据前状复发的，在上部的仍用吐药，在下部的仍用下药。这是再次入里的证候，是常事。甚至有复发三次的，也很少见。（以上论述邪气传入里部。）
如果服用达原饮后，或者因病失治，导致三阳经症状全部具备，里证也具备，而且舌根先出现白苔，到了此时舌根黄苔蔓延至中央，这是表里分传。其证候：外部则身热头痛，身疼，腰背项痛，眉棱痛，口苦耳聋，鼻干；内部则胸膈心腹满闷，下部热结。这是瘟疫病的常事，绝对不可强求发汗，适宜用承气汤先通利里部，里部邪气去除则气机通畅，乘势将邪气全部发散于肌表。如果表里症状全部消失而热仍不退（这是膜原的邪气未尽），适宜用三消饮：槟榔、草果、厚朴、白芍、甘草、知母、黄芩、大黄、干葛、羌活、柴胡，加姜、枣煎服，调理即可痊愈。服药痊愈后，过两三天复发的，仍用三消饮再次攻下和发汗，像前面那样痊愈，这也是常事。至于复发三次的，也很少。如果表邪多里证少，应当治表兼治里，用三消饮，大黄少量使用。如果里证多表证少，只治里，或用吐法或用下法，表证自然会愈。（以上论述表里分传。）
如果开始发病只是发热、头痛、身疼、口苦、鼻干，而内部没有里证，只适宜用达原饮加减法。如果没有出现三条经络的病证，仅仅发热，不用加法。继而脉象洪大数，自汗且口渴，邪气离开膜原，但未能出表，适宜用白虎汤辛凉解散，脉静身凉而痊愈。痊愈后数日又根据前状发热，仍适宜用达原饮。后来反而加上胸满腹胀，不思饮食，烦渴，舌上有刺等证，这都是由表传里导致的，达原饮加大黄轻微通利。久病不去，在上部的用吐方，在下部的用承气汤下方。如果开始时发热，渐渐成为里病，既然用了承气等汤剂攻下，里病就消除了。几天内又发热，反而加上头痛身疼，这是由里出表，脉浮的适宜用白虎汤。攻下后热减不明显，虽然热退，但有头痛身疼，而三四日后精神不振，脉浮的，也适宜用白虎汤发汗。如果服用白虎汤不得汗的，是因为精液枯竭，加人参，覆盖身体仰卧则汗出而解。如果在大攻下、大汗之后，表里症状全部消失，继而全身尽痛，身体像被棍棒打过一样，甚至不能翻身转动，周身骨节寒冷而痛（这是因为气血虚弱故痛），这不是表证，应当自愈。（以上论述表里递传。）
Plague (Wenyi) is not Cold Damage (Shanghan); physicians of the world mistakenly treat it as Cold Damage. Cold Damage results from contracting the normal Qi (regular climatic energy) of Heaven and Earth, whereas plague results from contracting the severe/pestilential Qi (epidemic toxic pathogens) of Heaven and Earth.
The pathogenic factor enters via the mouth and nose; internally it does not lodge in the Zang-Fu organs, externally it does not lodge in the meridians, but resides within the Mo Yuan (Membrane Source, located near the spine). This location is not far from the exterior, close to the Stomach, representing the boundary between Exterior and Interior. This corresponds to what the *Needle Classic* (*Zhen Jing*) refers to as "horizontally connecting the membrane source." Generally, when pathogens are in the meridians, it is an Exterior condition; when in the Stomach, it is an Interior condition. Now, with pathogens in the Mo Yuan, they are precisely at the junction where meridians and the Stomach intersect.
At the onset of the disease, there is shivering aversion to cold, which may progress to cold extremities (Jue Ni). When Yang heat becomes extremely stagnant and then unblocks, the cold extremities resolve, and heat manifests throughout the interior and exterior. Initially, there is aversion to cold, followed by fever; this differs from Cold Damage, where fever occurs simultaneously with aversion to cold. At the beginning of plague, there is first intense aversion to cold, then fever, accompanied by headache and body aches. The pulse is surging (Hong) and rapid (Shuo), neither floating nor sunken, because the pathogen is in the Mo Yuan.
It should not be mistaken for a Cold Damage Exterior syndrome treated with sweating methods; since the pathogen is not in the meridians, sweating will only injure healthy Qi in vain. Nor should purgation be used; since the pathogen is not in the Interior, purgation is of no benefit. It is appropriate to use Da Yuan Yin (Reach the Origin Decoction) to disperse and penetrate. The prescription consists of: Areca Seed (Binglang) 2 qian, Magnolia Bark (Houpo) 1 qian, Tsaoko Fruit (Caoguo) 0.5 qian, Anemarrhena Rhizome (Zhimu) 1 qian, Peony Root (Shaoyao) and Scutellaria Root (Huangqin) each 1 qian, Licorice Root (Gancao) 0.5 qian. Take warm in the afternoon. The first three herbs—Areca Seed, Magnolia Bark, and Tsaoko Fruit—eliminate stagnation and break accumulation, working together to drive out pathogens quickly from the Mo Yuan. The latter four herbs nourish fluids, harmonize blood, clear dryness-heat, and harmonize the Middle Jiao. (Note: This decoction is suitable for the initial stage; if the disease progresses to intense heat, this formula may be ineffective. If Exterior symptoms exist, Shuang Jie San (Double Release Powder) by Liu Hejian is appropriate; if no Exterior symptoms exist, Er Sheng Jiu Ku Dan (Two Sages' Saving Bitter Pill) by Li Dongyuan is appropriate. Other formulas such as Liang Ge San, Bai Hu Tang, Huang Lian Jie Du Tang, and Pu Ji Xiao Du Yin are also indicated based on the syndrome and can be used酌情ly.)
If the pathogenic factors overflow into different meridians, modifications to the base formula are as follows: Hypochondriac pain, deafness, alternating chills and fever, vomiting with bitter taste indicate pathogen overflowing into the Shaoyang Meridian; add Bupleurum Root (Chaihu) 1 qian. Pain in the lower back, back, and neck indicates pathogen overflowing into the Taiyang Meridian; add Notopterygium Root (Qianghuo) 1 qian. Eye pain, pain in the supraorbital ridge, orbital pain, dry nose, and insomnia indicate pathogen overflowing into the Yangming Meridian; add Kudzu Root (Gegen) 1 qian. If none of the Three Yang meridian syndromes appear, do not add herbs; follow the original formula. (Above discusses the use of Da Yuan Yin at onset.)
After taking this medicine, if the pathogen does not transmit to the Interior, it resolves spontaneously after one or two doses. The manifestations include headache and body aches, fever recurring with shivering, but without internal chest fullness or abdominal distension, normal appetite, no irritability or thirst. This indicates the pathogen is transmitting outward, exiting via the muscle layer. It may resolve through spontaneous eruption of macules/papules or through sweating. Macules/papules vary in type: macular rash, peach-blossom spots, purple cloud spots. Sweat varies: spontaneous sweat, night sweat, manic sweat. These differences are due to the nature of the disease qi; there is no need to debate them. As long as macules erupt or sweat appears, the disease is considered cured. This outward transmission is a favorable progression (Shun Zheng); even without medication, it may heal spontaneously.
If sweat is incomplete and fever persists, Bai Hu Tang (White Tiger Decoction) is appropriate: Gypsum (Shigao) 1 liang, Anemarrhena Rhizome (Zhimu) and Licorice Root (Gancao) each 5 qian, Rice (Jingmi) 1 pinch. This formula disperses with acrid-cool properties, resolving via shivering sweat or spontaneous sweat. Previously, Da Yuan Yin had begun to dissolve the toxin cluster, and the pathogen had left the Mo Yuan but had not yet fully reached the Exterior. However, the Qi of the interior and exterior was already communicating, hence the profuse sweating and long, surging, rapid pulse. Therefore, Bai Hu Tang is suitable to dissipate with acrid-cool action.
If macules/papules fail to emerge fully and fever persists, Ju Ban Tang (Lift Macules Decoction) is appropriate: White Peony Root (Baishao) and Angelica Sinensis Root (Danggui) each 1 qian, Cimicifuga Rhizome (Shengma) 0.5 qian, Angelica Dahurica Root (Baizhi) and Bupleurum Root (Chaihu) each 0.7 qian, Pangolin Scales (Chuanshanjia) 2 qian (fried until yellow). Decoct with water and fresh ginger.
If both macules/papules and sweat occur concurrently but fever persists, combine Bai Hu Tang with Ju Ban Tang.
After macules/papules and sweat have resolved, if fever recurs after one or two days or four or five days, without chest fullness or abdominal distension, and with a surging, rapid pulse, this indicates latent pathogens remaining in the Mo Yuan that were not fully dispersed. Without medication, spontaneous sweat or macule eruption should lead to recovery within one or two days. If unresolved, continue with previous methods; however, this is rare. Recurrent fever is even rarer. (Above discusses pathogen transmitting to the Exterior.)
If after taking Da Yuan Yin there is no sweat or macules, no external headache or body ache, but only chest and diaphragm stuffiness/fullness, this indicates pathogen transmitting to the Interior. Cases where there is an urge to vomit but inability to do so, or partial vomiting leaving discomfort, indicate pathogen transmitting to the Upper Interior; Dou Chi San (Melon Peduncle Powder) for emesis is appropriate. Melon Peduncle (Tianguadi) 1 qian, Red Adzuki Bean (Chixiaodou) 2 qian (ground), Gardenia Seed (Zhiren) 2 qian. Decoct 2 zhong of water to 1 zhong, add adzuki beans, simmer to 0.8 zhong. Take 0.4 zhong initially; if no vomiting after one hour, take again until fully vomited. If not fully expelled and irritability/fullness remain, decoct and take again. If melon peduncle is unavailable, substitute with Fermented Soybean (Danshidou) 2 qian. In this disease, inability to eat, chest/diaphragm irritability without abdominal fullness, vomiting reduces pathogen; once pathogen is gone, disease heals. Cases with heart/abdominal fullness, no vomiting, dry constipation, heat-binding with diarrhea, heat-binding with loose stools, or large intestine glue-like obstruction indicate pathogen transmitting to the Middle/Lower Interior; Cheng Qi Tang (Order the Qi Decoction) is appropriate: Rhubarb (Dahuang) 5 qian, Magnolia Bark (Houpo) 1 qian, Immature Bitter Orange (Zhishi) 1 qian, Mirabilite (Mangxiao) 2 qian. If only Upper Jiao stuffiness exists without constipation, remove Mangxiao to form Xiao Cheng Qi Tang (Minor Order the Qi Decoction). Even without hard stool, if feces are sticky and foul-smelling, add Mangxiao. If no stuffiness but only constipation, remove Houpo and Zhishi, use Mangxiao 2.5 qian, add Gancao 1 qian to form Tiao Wei Cheng Qi Tang (Regulate the Stomach Order the Qi Decoction). Taking this guides out the pathogen; as pathogen decreases, disease subsides; when pathogen is exhausted, disease cures itself.
Cases with chest/diaphragm fullness, heart/abdominal distension, and Lower Jiao heat-binding with stickiness involve both Upper and Middle Jiao. Emesis is contraindicated as it is adverse treatment. Using Cheng Qi Tang allows Upper pathogen to flow downward, stopping vomiting immediately and gradually relieving distension.
If after emesis or purgation the patient recovers, but relapses after two to five days according to previous symptoms, use emetics for Upper involvement and purgatives for Lower involvement. This recurrence of Interior transmission is common. Triple recurrence is rare. (Above discusses pathogen transmitting to the Interior.)
If after taking Da Yuan Yin, or due to mismanagement, all Three Yang symptoms and Interior symptoms present, and the tongue root shows white coating initially, progressing to yellow spreading to the center, this is simultaneous Exterior-Interior transmission. Manifestations: Externally, fever, headache, body ache, back/neck pain, supraorbital pain, bitter taste, deafness, dry nose; Internally, chest/diaphragm/heart/abdominal fullness, Lower Jiao heat-binding. This is common in plague. Do not force sweating. Use Cheng Qi Tang to first open the Interior. Once Interior pathogen is removed and Qi flows freely,顺势 release all pathogen to the muscle layer. If Exterior and Interior symptoms resolve but fever persists (indicating residual Mo Yuan pathogen), San Xiao Yin (Three Eliminations Decoction) is appropriate: Areca Seed (Binglang), Tsaoko Fruit (Caoguo), Magnolia Bark (Houpo), White Peony Root (Baishao), Licorice Root (Gancao), Anemarrhena Rhizome (Zhimu), Scutellaria Root (Huangqin), Rhubarb (Dahuang), Kudzu Root (Gegen), Notopterygium Root (Qianghuo), Bupleurum Root (Chaihu), Ginger, Jujube. Decoct and take; regulation leads to cure. If relapse occurs after two to three days post-cure, repeat San Xiao Yin for purgation and sweating as before; this is common. Triple recurrence is rare. If Exterior pathogen predominates over Interior syndrome, treat Exterior while addressing Interior using San Xiao Yin with minimal Dahuang. If Interior syndrome predominates over Exterior, treat only Interior using emesis or purgation; Exterior symptoms will resolve spontaneously. (Above discusses simultaneous Exterior-Interior transmission.)
If initial illness presents only with fever, headache, body ache, bitter taste, dry nose, without Interior symptoms, use modified Da Yuan Yin. If no Three Meridian syndromes appear and only fever exists, do not add herbs. If subsequently the pulse becomes surging, large, and rapid, with spontaneous sweat and thirst, the pathogen has left the Mo Yuan but cannot reach the Exterior; use Bai Hu Tang to disperse with acrid-cool action. Recovery occurs when pulse calms and body cools. If fever recurs several days after recovery, use Da Yuan Yin again. If later chest/abdominal fullness, anorexia, irritability/thirst, and prickly tongue coating appear, these result from Exterior transmitting to Interior; add Dahuang to Da Yuan Yin for mild purgation. If prolonged without resolution, use emetics for Upper involvement and Cheng Qi Tang for Lower involvement. If initial fever gradually becomes Interior disease, and Cheng Qi Tang etc. are used to purge, Interior disease is cleared. If fever recurs within a few days, accompanied by headache and body ache, this is Interior transmitting to Exterior; if pulse is floating, use Bai Hu Tang. If after purgation fever decreases slightly, or fever is absent but headache/body ache persist, and after three to four days spirit is dull with floating pulse, use Bai Hu Tang to induce sweating. If Bai Hu Tang fails to induce sweat, it is due to depletion of essence/fluids; add Ginseng (Renshen), cover the patient, lie supine, and sweat will resolve. After severe purgation or profuse sweating, if all Exterior-Interior symptoms resolve, followed by generalized body pain, feeling as if beaten by a club, inability to turn, and cold painful bones throughout the body (due to deficiency of Qi and Blood), this is not an Exterior syndrome; it will heal spontaneously. (Above discusses sequential Exterior-Interior transmission.)